UDP-glucose dehydrogenase catalyzes the conversion of UDP-glucose to UDP-glucuronic acid a precursor of hemicellulose. Hemicellulose is a major component of primary plant cell walls. Many of the glycosyl residues found in hemicellulose are derived from the sugar precursor UDP-glucuronic acid, which can be converted into UDP-arabinose, UDP-apiose, UDP-galacturonic acid, and UDP-xylose. The synthesis of non-cellulosic cell wall polysaccharides, a major component of plant cell walls, is directed through the enzyme, UDP-glucose dehydrogenase. This enzyme has been shown to be the rate limiting step in the biosynthesis of non-cellulosic polysaccharides, suggesting it is a key regulatory step in cell wall synthesis. It has been shown that over expression of UDP-glucose dehydrogenase in transgenic plants caused a 50% increase in leaf elongation rate (LER) compared to wildtype (Cramer, G. R., et al., (1998) The American Society of Plant Physiologists Annual Meeting, Session #39, Abstract #332). The enzyme is highly expressed in young roots, but lower expression levels have been observed in expanding tissues of the epicotyl and in young leaves. The expression pattern of the enzyme in different developmental stages strengthens the argument that UDP-glucose dehydrogenase is a key regulator for the availability of hemicellulose precursors. Thus, it appears that biosynthesis of cell wall components is a rate-limiting step for cell expansion and plant growth and that UDP-glucose dehydrogenase may be a powerful new tool to manipulate the growth of plants.